1. Field of the Invention
The present invention relates to a method for manufacturing an image display device.
2. Description of the Related Art Conventional electron emitting devices are generally classified into two types of devices, i.e., thermionic cathode type devices and cold cathode type devices. The cold cathode type devices include field emission type devices, metal/insulating-layer/metal type devices, surface conduction type devices and the like.
The surface conduction type electron emitting devices utilize the phenomenon that electron emission occurs by passing a current in a direction parallel to the surface of a small-area thin film formed on a substrate. The assignee of the present application has provided a large number of proposals with respect to surface conduction type electron emitting devices having new configurations and applications thereof. The basic configurations and manufacturing methods of such devices are disclosed, for example, in Japanese Patent Application Laid-Open (Kokai) Nos. 7-235255 (1995), 8-171849 (1996), 2000-311594 (2000) and 11-195374 (1999), and EP-A No. 0908916.
The surface conduction type electron emitting devices have the feature that a pair of electrodes facing each other, and a conductive film connected to the pair of electrodes and having a gap in a part of the film are provided on a substrate.
A carbon film having at least one of carbon and a carbon compound as a main component is provided in the gap.
By providing a plurality of such electron emitting devices on a substrate and connecting the devices by wires, an electron source including a plurality of surface conduction type electron emitting devices can be manufactured.
By combining the electron source with a phosphor, an image display device can be formed.
Conventionally, such an electron source and an image display device are manufactured in the following manner.
In a first manufacturing method, first, a plurality of units, each including a conductive film and a pair of electrodes connected thereto, and wires connected to the electrodes are each formed on a substrate. Then, the entirety of the formed units on the substrate is placed in a vacuum chamber. After evacuating the vacuum chamber, a gap is formed in the conductive film of each of the units by applying a voltage to the unit through external terminals (a xe2x80x9cformingxe2x80x9d process). Then, a gag of a carbon compound is introduced into the vacuum chamber, and a voltage is again applied to each of the units in this atmosphere through the external terminals. By this voltage application, a carbon film having at least one of carbon and the carbon compound as a main component is formed in a portion including the gap (an xe2x80x9cactivatingxe2x80x9d process). As a result, an electron source is formed having the substrate and the plurality of electron emitting devices. Then, the panel of an image display device is manufactured by connecting the electron source and a substrate on which a phosphor is disposed, with an interval of a few millimeters provided between those components.
In a second manufacturing method, first, a plurality of units, each including a conductive film and a pair of electrodes connected thereto, and wires connected to the electrodes of the plurality of units are each formed on a substrate. Then, the panel of an image display device is manufactured by connecting the formed substrate and a substrate on which a phosphor is disposed, with an interval of a few millimeters being provided between them. Then, the inside of the panel is evacuated through an exhaust tube connected to the panel. Then, a gap is formed in the conductive film of each of the units by applying a voltage to the unit through external terminals of the panel (the xe2x80x9cformingxe2x80x9d process). Then, a gas of a carbon compound is introduced into the panel through the exhaust tube, and a voltage is again applied to each of the units in this atmosphere through the external terminals. By this voltage application, a carbon film having at least one of carbon and the carbon is compound as a main component is formed in a portion including the gap (the xe2x80x9cactivatingxe2x80x9d process). As a result, an electron source is provided having a plurality of electron emitting devices formed on a substrate.
In the conventional methods for manufacturing en electron source and an image display device, the above-described xe2x80x9cformingxe2x80x9d and xe2x80x9cactivatingxe2x80x9d processes are adopted. However, in the above-described first manufacturing method, as the size of the electron-source substrate is larger, a larger vacuum chamber and an evacuation apparatus having a larger pumping speed are required. In the second manufacturing method, a long time is required for both evacuation of a small space within the panel in the xe2x80x9cformingxe2x80x9d process, and uniform introduction of the gas used in the xe2x80x9cactivatingxe2x80x9d process into the panel and the succeeding evacuation of the gas.
It is an object of the present invention to provide a method for manufacturing an electron source and an image display device in which the speed of the xe2x80x9cactivatingxe2x80x9d process is increased and the uniformity of electron emission characteristics is improved, and which is suitable for mass production.
It is another object of the present invention to provide an image display device and a method for manufacturing the same in which an electron source having excellent electron emission characteristics can be manufactured, and wherein stable vacuum tightness is maintained by a substrate having an electron source formed thereon and a substrate having a phosphor formed thereon, disposed so as to face the first substrate.
The inventor of the present invention has discovered the following novel aspects of the invention as a result of keen investigations.
According to one aspect, the present invention which achieves these objectives relates to a method for manufacturing an image display device. The method includes the steps of disposing a first substrate on a supporting member, the first substrate having conductors and wires connected to the conductors mounted thereon, and covering a part of the first substrate with a container to thereby dispose the conductors within a space formed between the first substrate and the container. Part of the wires is disposed outside of the space. The method also includes the steps of providing the space formed between the container and the first substrate with a desired atmosphere, applying a voltage to the conductors through the part of the wires disposed outside of the space, removing the container from the first substrate, and connecting a second substrate including an image forming member via a connecting member, to a region of the first substrate different from a region where the container and the first substrate were connected together.
According to another aspect, the present invention which achieves these objectives relates to another method for manufacturing an image display device. The method includes a step of disposing a first substrate on a supporting member, the first substrate having mounted thereon a plurality of units and wires connecting the plurality of units. Each unit includes a pair of electrodes and a conductive film disposed between the pair of electrodes. A next step includes covering a part of the first substrate with the container, and thereby disposing the plurality of units within a space formed between the first substrate and the container. Part of the wires is disposed outside of the space. The method also includes the steps of providing the space formed between the container and the first substrate with a desired atmosphere, converting each of the plurality of units to an electron emitting device by applying a voltage to the plurality of units through the part of the wires disposed outside of the space, removing the container from the first substrate, and connecting a second substrate including an image forming member to the first substrate, via connecting member, at a region different from a region where the container and the first substrate were connected together.
According to still another aspect, the present invention which achieves these objectives relates to a further method for manufacturing an image display device. The method includes a step of disposing a first substrate on a supporting member, the first substrate having mounted thereon a plurality of units, a plurality of x-direction wires and a plurality of y-direction wires connected to the plurality of units. Each unit includes a pair of electrodes and a conductive film disposed between the pair of electrodes. A next step includes covering a part of the first substrate with the container, and thereby disposing the plurality of units within a space formed between the first substrate and the container. Part of the plurality of x-direction wires and the plurality of y-direction wires is disposed outside of the space. The method also includes the steps of providing the space formed between the container and the first substrate with a desired atmosphere, converting each of the plurality of units into an electron emitting device by applying a voltage to the plurality of units through the part of the plurality of x-direction wires and the plurality of y-direction wires disposed outside of the space, removing the container from the first substrate, and connecting a second substrate including an image forming member to the first substrate via a connecting member, at a region of the first substrate different from a region where the container and the first substrate were connected together.
An apparatus for manufacturing an electron-source substrate and an image display device according to the present invention includes a supporting member for supporting a substrate on which conductors are formed, and a container covering the substrate supported by the supporting member.
The container covers a part of the surface of the substrate, and can thereby form an airtight space on the substrate in a state in which part of wires formed on the substrate in a state of being connected to the conductors is exposed outside the container. An inlet and an outlet for a gas are provided at the container. Means for guiding the gas into the container and means for exhausting the gas from the container are connected to the inlet and the outlet, respectively. It is thereby possible to set the inside of the container to a desired atmosphere. An electron source is formed by the substrate and electron emitting portions formed thereon according to electric processing.
Accordingly, the above-described manufacturing apparatus also includes means for performing electric processing, such as means for applying a voltage to the conductors. In this manufacturing apparatus, it is possible to reduce the size of the apparatus, achieve a simple operability, for example, in electric connection to a power supply in the electric processing, increase the degree of freedom in the design of the size, the shape and the like of the container, and perform introduction of the gas into the container and exhaust of the gas to the outside of the container in a short time.
In the manufacturing method, first, the substrate on which the conductors and the wires connected to the conductors are formed is disposed on the supporting member, and the conductors on the substrate are covered with the container except for part of the wires. Thus, the conductors are disposed in the airtight space formed on the substrate in a state in which part of the wires formed on the substrate is exposed outside of the container.
Then, the inside of the container is set to a desired atmosphere, and electric processing is performed by, for example, application of a voltage to the conductors through the part of the wires exposed outside of the container. The desired atmosphere is, for example, a low-pressure atmosphere, or an atmosphere in which a specific gas is present. The electric processing causes the electron source to be formed by forming the electron emitting portions (which partially include the conductors). The electric processing may be performed a plurality of times in different atmospheres, depending on applicable design criteria.
For example, the conductors on the substrate are covered by the container except for part of the wires. First, the step of providing the inside of the container with a first atmosphere is performed. Then, the step of providing the inside of the container with a second atmosphere is performed. Thus, as a result, an electron source is manufactured by forming electron emitting portions in the conductors.
The first atmosphere preferably is a low-pressure atmosphere, and the second atmosphere preferably is an atmosphere in which a specific gas, such as a carbon compound or the like, is present.
In the above-described manufacturing method, it is possible to easily perform electric connection to the power supply in the electric processing since part of the wires connected to the conductors is disposed outside of the container. Since the degree of freedom in the design of the size, the shape and the like of the container is increased, it is possible to perform introduction of the gas into the container and exhaust of the gas to the outside of the container in a short time, improve the manufacturing speed, and improve the reproducibility of the electron emission characteristics of the manufactured electron source, particularly, uniformity in the electron emission characteristics of the plurality of electron emitting portions.
The electron-source substrate manufactured in the above-described manner and another substrate having a phosphor formed thereon are connected via a frame member using frit glass or the like so as to maintain a constant interval between the two substrates. Preferably, the region of the electron-source substrate where the other substrate contacts the electron-source substrate is different from the region where the container contacted the electron-source substrate. Accordingly, the connection between the electron-source substrate and the other substrate having the phosphor formed thereon via the frame member is not influenced by adhesion of components of a vacuum-tight member provided in the container when connected to the electron-source substrate, and a stable connection and reliable provision of a vacuum can be realized.